The present invention relates to a method for automatically addressing a plurality of mobile substations from a central station, the mobile stations being arranged in series. More particularly, the present invention relates to a method wherein a double-wire line serves to transmit information in two frequency channels with orders and reports being transmitted in sequence. The invention is also directed towards a circuit arrangement for carrying out this method.
One field of use of the invention resides in the sector of transportion; for example for controlling trains in a railway network, and preferably in trains with center buffer coupling. This invention has particular use in connection with the automation of train operations such as the German Federal Railway, by remote action devices on the train.
In "Ein Fernwirksystem zur automatischen Meldungsund Befehlsubertragung innerhalb von Zugverbanden" (A remote action system for automatic transmission of reports and orders within connection trains) by H.-H. Muller and K.-M. Schultze, published in Techn. Mitt. AEG-Telefunken 61 (1971) 6, pages 318 to 320, there is described a remote-action system which automatically addresses railroad cars which are connected to form a train and cyclically checks the completeness of the entire train. This system was developed to transmit orders and reports in trains of the European railway network after introduction of the automatic center buffer coupling. This future automatic coupling will simultaneously couple, among other things, electric lines. In this way the prerequisities are created for introducing a system for the transmission of information in the train.
With the known combination of a cyclic and a spontaneous transmission system, the condition of the train (for example, the completeness of the train and breakdown and operating reports) can be sent from a plurality of substations (for example, each individual car) to a central station (for example, the cab of the motor car). Orders (for example "uncouple", "close doors", etc.) may also be transmitted from the central station to the substations. This information is transmitted within the train over a two-wire line using a time division multiplex signal.
After the train has been assembled (i.e., cab and cars placed together to form a train) and the information line has been connected through the train, the addressing process is initiated by a voltage pulse which effects in each car the opening of a normally closed relay contact thus effecting the opening of the information line. At the same time, a terminal resistance is placed in front of and behind the open contact on the line. An orienting device in the coach determines the direction criterion, i.e. the direction of the corresponding coach with respect to the locomotive. The addressing process terminates when the number of coaches detected during the addressing sequence agrees with a predetermined desired value. After the addressing, operation, safety and breakdown reports as well as orders can be transmitted between the central station and substations.
The above known arrangement has several drawbacks. With long trains there is extensive dampening on the information line due to two factors: (1) all transmitting and receiving devices lie in parallel on the line and (2) a large number of coupling and relay contacts are arranged in the course of the line. The large number of contacts also results in a lack of reliability and an increased safety risk. Furthermore, a complicated insertion of terminal resistances is required and disadvantageous. A further drawback of this system lies in the fact that recognition of the direction is complicated and sensitive to disturbances.
In the article "Zeitmultiplexe Wendezugsteuerung" (Time Division-Multiplex Reversible Train Control) by W. Deck and R. Schneider, published in BBC-Nachrichten (1976), issue 2/3, pages 103-108, a remote action system for push-pull operation is described. In this operation the locomotive alternately pushes and pulls the train to avoid the need to switch the locomotive before changing the direction of travel of the train. In the case of push-pull trains a control car, which houses all of the important control and indicating circuits, travels at the opposite end of the train from the locomotive. The frequency band for the transmission of information for the push-pull control is divided into three channels: channel 1 from control car to locomotive; channel 2 from the first locomotive to the control car; channel 3 from the second locomotive to the control car. Channel 3 permits the expanding of the system to double heading. In this type of operation the train set consists of two locomotives, a control car and additional cars.
The solution of the problem of double-heating by means of a third frequency channel has, however, numerous disadvantages. The expense required is very great, since additional receiving devices must be provided to handle the third channel. Additionally, each locomotive must have transmitting apparatus for all three channels. After the forming of each train, manual switching operations must be effected depending on the type of operation, namely "single heading", "double heading", or "double heading without push-pull control", and this must be checked, which results in complicated operating instructions for the train personnel.
The object of the present invention is to develop a remote-action system for automatically addressing a plurality of mobile substations from a central station. In the case of a train, for instance, the central station may be a locomotive or a control car while the substations are represented by another locomotive and other cars. The central station is, in this connection, to be connected to the substations only by a two-wire line.
Other special objects of the invention lie in the development of an automatic direction recognition, i.e. recognition of the direction of the central station relative to the substations. Additionally, it should be possible to use the information transmission line for other purposes, i.e. alternating voltages of all frequencies, including direct current voltages, should be capble of being transmitted.